Human Energy Systems | Activity 4.5

Use Slides 3-5 to remind students of the pools and fluxes that they have used in previous models and how they can be used to explain the seasonal patterns and long-term trend in the Keeling Curve.

Use Slide 6 to introduce and discuss that two goals for this lesson.

Show the NOAA “Pumphandle” video

Use Slide 7 to lead a discussion of different patterns that they notice in the Northern and Southern Hemispheres. See the Lesson 4 Background information for more information about this video.

Use Slide 8 and the associated video to discuss the different annual patterns:

• In Hawaii CO₂ concentrations rise to a peak in May, then fall during the Northern Hemisphere summer.
• At the South Pole CO₂ concentrations rise to a peak in October, then fall during the Northern Hemisphere winter.

Use Slide 9 to show students how photosynthesis fluxes in the Northern and Southern Hemispheres change across the seasons.

Use Slide 10 to have students describe the pattern:

• The Northern Hemisphere photosynthesis flux peaks in the Northern Hemisphere summer (around July).
• The Southern Hemisphere photosynthesis flux peaks in the Southern Hemisphere summer (around January).

Pass out the 4.5 Seasons and Oceans Worksheet.

Show Slides 11 and 12 and remind students about how they can use the Four Questions to guide their writing of a good explanation.

Show Slide 13 and have students complete Part A of the worksheet before continuing the lesson.

Slides 14-18 show correct answers to each of the Four Questions and to each question in Part A of the 4.5 Seasons and Oceans Worksheet. Show these slides and have students check, discuss, and revise their own answers to the worksheet questions.

Show Slides 19 to introduce the second goal for this activity: figuring out how other pools and fluxes affect atmospheric CO₂.

Use Slide 20 to elicit students’ ideas about other pools and fluxes that are not included in the models that they have been using.

Use Slide 21 to introduce the Global Carbon Cycling Diagram (based on data from the Global Carbon Project: www.carsclimate.com blog.) Note the new pools and fluxes:

• The oceans are the other major pool that was not included in the models used earlier in this lesson. There are fluxes into the ocean (when CO₂ dissolves in water) and out of the ocean (when CO₂ vaporizes from water, like soda water losing its fizz).
• Land use change (such as forests being converted to farms or cities) affects fluxes into and out of vegetation and the soil organic carbon pool.

Show Slides 22 and 23 to remind students that they can use the rules for pools and fluxes (from Activity 4.3: Tiny World Modeling) to calculate how the atmospheric carbon pool is changing.

After students have tried their calculations, use Slide 24 to show a way to calculate the overall net flux of carbon into the atmosphere.

Slide 25 provides a link to more information about the effects of the carbon flux into the oceans.

Slide 26 reminds students of the Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half Ask students if they can use the Global Carbon Cycling Diagram to calculate and answer to that question.

Have students complete Part B of 4.5 Seasons and Oceans Worksheet.

Have students check their calculations against those on Slide 28.

Show Slide 29 of the 4.5 Seasons & Oceans PPT.

• Have students take out their Learning Tracking Tool from the previous lesson.
• Have students write the activity name in the first column, "4.5 Effects of Seasons and Oceans."
• Have a class discussion about what students figured out during the activity that will help them in answering the lesson driving questions:
• What causes the annual cycle: CO₂ concentrations in Hawaii to go down every summer and up every winter?
• What causes the long-term trend: CO₂ concentrations to go up every year?
• How can we predict what will happen to CO₂ concentrations in the future?
• When you come to consensus as a class, have students record the answer in the second column of the tool.
• Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the third column of the tool.
• Have students keep their Learning Tracking Tool for future activities.
• Example Learning Tracking Tool